930be3aa80cf7e69e49b730a07e794c0d0a0feee
[sfrench/cifs-2.6.git] / ipc / shm.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * linux/ipc/shm.c
4  * Copyright (C) 1992, 1993 Krishna Balasubramanian
5  *       Many improvements/fixes by Bruno Haible.
6  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
7  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
8  *
9  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
10  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
11  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
12  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
13  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
14  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
15  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
16  *
17  * support for audit of ipc object properties and permission changes
18  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
19  *
20  * namespaces support
21  * OpenVZ, SWsoft Inc.
22  * Pavel Emelianov <xemul@openvz.org>
23  *
24  * Better ipc lock (kern_ipc_perm.lock) handling
25  * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
26  */
27
28 #include <linux/slab.h>
29 #include <linux/mm.h>
30 #include <linux/hugetlb.h>
31 #include <linux/shm.h>
32 #include <linux/init.h>
33 #include <linux/file.h>
34 #include <linux/mman.h>
35 #include <linux/shmem_fs.h>
36 #include <linux/security.h>
37 #include <linux/syscalls.h>
38 #include <linux/audit.h>
39 #include <linux/capability.h>
40 #include <linux/ptrace.h>
41 #include <linux/seq_file.h>
42 #include <linux/rwsem.h>
43 #include <linux/nsproxy.h>
44 #include <linux/mount.h>
45 #include <linux/ipc_namespace.h>
46
47 #include <linux/uaccess.h>
48
49 #include "util.h"
50
51 struct shmid_kernel /* private to the kernel */
52 {
53         struct kern_ipc_perm    shm_perm;
54         struct file             *shm_file;
55         unsigned long           shm_nattch;
56         unsigned long           shm_segsz;
57         time64_t                shm_atim;
58         time64_t                shm_dtim;
59         time64_t                shm_ctim;
60         struct pid              *shm_cprid;
61         struct pid              *shm_lprid;
62         struct user_struct      *mlock_user;
63
64         /* The task created the shm object.  NULL if the task is dead. */
65         struct task_struct      *shm_creator;
66         struct list_head        shm_clist;      /* list by creator */
67 } __randomize_layout;
68
69 /* shm_mode upper byte flags */
70 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
71 #define SHM_LOCKED      02000   /* segment will not be swapped */
72
73 struct shm_file_data {
74         int id;
75         struct ipc_namespace *ns;
76         struct file *file;
77         const struct vm_operations_struct *vm_ops;
78 };
79
80 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
81
82 static const struct file_operations shm_file_operations;
83 static const struct vm_operations_struct shm_vm_ops;
84
85 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
86
87 #define shm_unlock(shp)                 \
88         ipc_unlock(&(shp)->shm_perm)
89
90 static int newseg(struct ipc_namespace *, struct ipc_params *);
91 static void shm_open(struct vm_area_struct *vma);
92 static void shm_close(struct vm_area_struct *vma);
93 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
94 #ifdef CONFIG_PROC_FS
95 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
96 #endif
97
98 int shm_init_ns(struct ipc_namespace *ns)
99 {
100         ns->shm_ctlmax = SHMMAX;
101         ns->shm_ctlall = SHMALL;
102         ns->shm_ctlmni = SHMMNI;
103         ns->shm_rmid_forced = 0;
104         ns->shm_tot = 0;
105         return ipc_init_ids(&shm_ids(ns));
106 }
107
108 /*
109  * Called with shm_ids.rwsem (writer) and the shp structure locked.
110  * Only shm_ids.rwsem remains locked on exit.
111  */
112 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
113 {
114         struct shmid_kernel *shp;
115
116         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
117
118         if (shp->shm_nattch) {
119                 shp->shm_perm.mode |= SHM_DEST;
120                 /* Do not find it any more */
121                 ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
122                 shm_unlock(shp);
123         } else
124                 shm_destroy(ns, shp);
125 }
126
127 #ifdef CONFIG_IPC_NS
128 void shm_exit_ns(struct ipc_namespace *ns)
129 {
130         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
131         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
132         rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
133 }
134 #endif
135
136 static int __init ipc_ns_init(void)
137 {
138         const int err = shm_init_ns(&init_ipc_ns);
139         WARN(err, "ipc: sysv shm_init_ns failed: %d\n", err);
140         return err;
141 }
142
143 pure_initcall(ipc_ns_init);
144
145 void __init shm_init(void)
146 {
147         ipc_init_proc_interface("sysvipc/shm",
148 #if BITS_PER_LONG <= 32
149                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
150 #else
151                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
152 #endif
153                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
154 }
155
156 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
157 {
158         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
159
160         if (IS_ERR(ipcp))
161                 return ERR_CAST(ipcp);
162
163         return container_of(ipcp, struct shmid_kernel, shm_perm);
164 }
165
166 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
167 {
168         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
169
170         if (IS_ERR(ipcp))
171                 return ERR_CAST(ipcp);
172
173         return container_of(ipcp, struct shmid_kernel, shm_perm);
174 }
175
176 /*
177  * shm_lock_(check_) routines are called in the paths where the rwsem
178  * is not necessarily held.
179  */
180 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
181 {
182         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
183
184         /*
185          * Callers of shm_lock() must validate the status of the returned ipc
186          * object pointer (as returned by ipc_lock()), and error out as
187          * appropriate.
188          */
189         if (IS_ERR(ipcp))
190                 return (void *)ipcp;
191         return container_of(ipcp, struct shmid_kernel, shm_perm);
192 }
193
194 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
195 {
196         rcu_read_lock();
197         ipc_lock_object(&ipcp->shm_perm);
198 }
199
200 static void shm_rcu_free(struct rcu_head *head)
201 {
202         struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
203                                                         rcu);
204         struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
205                                                         shm_perm);
206         security_shm_free(&shp->shm_perm);
207         kvfree(shp);
208 }
209
210 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
211 {
212         list_del(&s->shm_clist);
213         ipc_rmid(&shm_ids(ns), &s->shm_perm);
214 }
215
216
217 static int __shm_open(struct vm_area_struct *vma)
218 {
219         struct file *file = vma->vm_file;
220         struct shm_file_data *sfd = shm_file_data(file);
221         struct shmid_kernel *shp;
222
223         shp = shm_lock(sfd->ns, sfd->id);
224
225         if (IS_ERR(shp))
226                 return PTR_ERR(shp);
227
228         if (shp->shm_file != sfd->file) {
229                 /* ID was reused */
230                 shm_unlock(shp);
231                 return -EINVAL;
232         }
233
234         shp->shm_atim = ktime_get_real_seconds();
235         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
236         shp->shm_nattch++;
237         shm_unlock(shp);
238         return 0;
239 }
240
241 /* This is called by fork, once for every shm attach. */
242 static void shm_open(struct vm_area_struct *vma)
243 {
244         int err = __shm_open(vma);
245         /*
246          * We raced in the idr lookup or with shm_destroy().
247          * Either way, the ID is busted.
248          */
249         WARN_ON_ONCE(err);
250 }
251
252 /*
253  * shm_destroy - free the struct shmid_kernel
254  *
255  * @ns: namespace
256  * @shp: struct to free
257  *
258  * It has to be called with shp and shm_ids.rwsem (writer) locked,
259  * but returns with shp unlocked and freed.
260  */
261 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
262 {
263         struct file *shm_file;
264
265         shm_file = shp->shm_file;
266         shp->shm_file = NULL;
267         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
268         shm_rmid(ns, shp);
269         shm_unlock(shp);
270         if (!is_file_hugepages(shm_file))
271                 shmem_lock(shm_file, 0, shp->mlock_user);
272         else if (shp->mlock_user)
273                 user_shm_unlock(i_size_read(file_inode(shm_file)),
274                                 shp->mlock_user);
275         fput(shm_file);
276         ipc_update_pid(&shp->shm_cprid, NULL);
277         ipc_update_pid(&shp->shm_lprid, NULL);
278         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
279 }
280
281 /*
282  * shm_may_destroy - identifies whether shm segment should be destroyed now
283  *
284  * Returns true if and only if there are no active users of the segment and
285  * one of the following is true:
286  *
287  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
288  *
289  * 2) sysctl kernel.shm_rmid_forced is set to 1.
290  */
291 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
292 {
293         return (shp->shm_nattch == 0) &&
294                (ns->shm_rmid_forced ||
295                 (shp->shm_perm.mode & SHM_DEST));
296 }
297
298 /*
299  * remove the attach descriptor vma.
300  * free memory for segment if it is marked destroyed.
301  * The descriptor has already been removed from the current->mm->mmap list
302  * and will later be kfree()d.
303  */
304 static void shm_close(struct vm_area_struct *vma)
305 {
306         struct file *file = vma->vm_file;
307         struct shm_file_data *sfd = shm_file_data(file);
308         struct shmid_kernel *shp;
309         struct ipc_namespace *ns = sfd->ns;
310
311         down_write(&shm_ids(ns).rwsem);
312         /* remove from the list of attaches of the shm segment */
313         shp = shm_lock(ns, sfd->id);
314
315         /*
316          * We raced in the idr lookup or with shm_destroy().
317          * Either way, the ID is busted.
318          */
319         if (WARN_ON_ONCE(IS_ERR(shp)))
320                 goto done; /* no-op */
321
322         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
323         shp->shm_dtim = ktime_get_real_seconds();
324         shp->shm_nattch--;
325         if (shm_may_destroy(ns, shp))
326                 shm_destroy(ns, shp);
327         else
328                 shm_unlock(shp);
329 done:
330         up_write(&shm_ids(ns).rwsem);
331 }
332
333 /* Called with ns->shm_ids(ns).rwsem locked */
334 static int shm_try_destroy_orphaned(int id, void *p, void *data)
335 {
336         struct ipc_namespace *ns = data;
337         struct kern_ipc_perm *ipcp = p;
338         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
339
340         /*
341          * We want to destroy segments without users and with already
342          * exit'ed originating process.
343          *
344          * As shp->* are changed under rwsem, it's safe to skip shp locking.
345          */
346         if (shp->shm_creator != NULL)
347                 return 0;
348
349         if (shm_may_destroy(ns, shp)) {
350                 shm_lock_by_ptr(shp);
351                 shm_destroy(ns, shp);
352         }
353         return 0;
354 }
355
356 void shm_destroy_orphaned(struct ipc_namespace *ns)
357 {
358         down_write(&shm_ids(ns).rwsem);
359         if (shm_ids(ns).in_use)
360                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
361         up_write(&shm_ids(ns).rwsem);
362 }
363
364 /* Locking assumes this will only be called with task == current */
365 void exit_shm(struct task_struct *task)
366 {
367         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
368         struct shmid_kernel *shp, *n;
369
370         if (list_empty(&task->sysvshm.shm_clist))
371                 return;
372
373         /*
374          * If kernel.shm_rmid_forced is not set then only keep track of
375          * which shmids are orphaned, so that a later set of the sysctl
376          * can clean them up.
377          */
378         if (!ns->shm_rmid_forced) {
379                 down_read(&shm_ids(ns).rwsem);
380                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
381                         shp->shm_creator = NULL;
382                 /*
383                  * Only under read lock but we are only called on current
384                  * so no entry on the list will be shared.
385                  */
386                 list_del(&task->sysvshm.shm_clist);
387                 up_read(&shm_ids(ns).rwsem);
388                 return;
389         }
390
391         /*
392          * Destroy all already created segments, that were not yet mapped,
393          * and mark any mapped as orphan to cover the sysctl toggling.
394          * Destroy is skipped if shm_may_destroy() returns false.
395          */
396         down_write(&shm_ids(ns).rwsem);
397         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
398                 shp->shm_creator = NULL;
399
400                 if (shm_may_destroy(ns, shp)) {
401                         shm_lock_by_ptr(shp);
402                         shm_destroy(ns, shp);
403                 }
404         }
405
406         /* Remove the list head from any segments still attached. */
407         list_del(&task->sysvshm.shm_clist);
408         up_write(&shm_ids(ns).rwsem);
409 }
410
411 static int shm_fault(struct vm_fault *vmf)
412 {
413         struct file *file = vmf->vma->vm_file;
414         struct shm_file_data *sfd = shm_file_data(file);
415
416         return sfd->vm_ops->fault(vmf);
417 }
418
419 static int shm_split(struct vm_area_struct *vma, unsigned long addr)
420 {
421         struct file *file = vma->vm_file;
422         struct shm_file_data *sfd = shm_file_data(file);
423
424         if (sfd->vm_ops->split)
425                 return sfd->vm_ops->split(vma, addr);
426
427         return 0;
428 }
429
430 #ifdef CONFIG_NUMA
431 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
432 {
433         struct file *file = vma->vm_file;
434         struct shm_file_data *sfd = shm_file_data(file);
435         int err = 0;
436
437         if (sfd->vm_ops->set_policy)
438                 err = sfd->vm_ops->set_policy(vma, new);
439         return err;
440 }
441
442 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
443                                         unsigned long addr)
444 {
445         struct file *file = vma->vm_file;
446         struct shm_file_data *sfd = shm_file_data(file);
447         struct mempolicy *pol = NULL;
448
449         if (sfd->vm_ops->get_policy)
450                 pol = sfd->vm_ops->get_policy(vma, addr);
451         else if (vma->vm_policy)
452                 pol = vma->vm_policy;
453
454         return pol;
455 }
456 #endif
457
458 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
459 {
460         struct shm_file_data *sfd = shm_file_data(file);
461         int ret;
462
463         /*
464          * In case of remap_file_pages() emulation, the file can represent an
465          * IPC ID that was removed, and possibly even reused by another shm
466          * segment already.  Propagate this case as an error to caller.
467          */
468         ret = __shm_open(vma);
469         if (ret)
470                 return ret;
471
472         ret = call_mmap(sfd->file, vma);
473         if (ret) {
474                 shm_close(vma);
475                 return ret;
476         }
477         sfd->vm_ops = vma->vm_ops;
478 #ifdef CONFIG_MMU
479         WARN_ON(!sfd->vm_ops->fault);
480 #endif
481         vma->vm_ops = &shm_vm_ops;
482         return 0;
483 }
484
485 static int shm_release(struct inode *ino, struct file *file)
486 {
487         struct shm_file_data *sfd = shm_file_data(file);
488
489         put_ipc_ns(sfd->ns);
490         fput(sfd->file);
491         shm_file_data(file) = NULL;
492         kfree(sfd);
493         return 0;
494 }
495
496 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
497 {
498         struct shm_file_data *sfd = shm_file_data(file);
499
500         if (!sfd->file->f_op->fsync)
501                 return -EINVAL;
502         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
503 }
504
505 static long shm_fallocate(struct file *file, int mode, loff_t offset,
506                           loff_t len)
507 {
508         struct shm_file_data *sfd = shm_file_data(file);
509
510         if (!sfd->file->f_op->fallocate)
511                 return -EOPNOTSUPP;
512         return sfd->file->f_op->fallocate(file, mode, offset, len);
513 }
514
515 static unsigned long shm_get_unmapped_area(struct file *file,
516         unsigned long addr, unsigned long len, unsigned long pgoff,
517         unsigned long flags)
518 {
519         struct shm_file_data *sfd = shm_file_data(file);
520
521         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
522                                                 pgoff, flags);
523 }
524
525 static const struct file_operations shm_file_operations = {
526         .mmap           = shm_mmap,
527         .fsync          = shm_fsync,
528         .release        = shm_release,
529         .get_unmapped_area      = shm_get_unmapped_area,
530         .llseek         = noop_llseek,
531         .fallocate      = shm_fallocate,
532 };
533
534 /*
535  * shm_file_operations_huge is now identical to shm_file_operations,
536  * but we keep it distinct for the sake of is_file_shm_hugepages().
537  */
538 static const struct file_operations shm_file_operations_huge = {
539         .mmap           = shm_mmap,
540         .fsync          = shm_fsync,
541         .release        = shm_release,
542         .get_unmapped_area      = shm_get_unmapped_area,
543         .llseek         = noop_llseek,
544         .fallocate      = shm_fallocate,
545 };
546
547 bool is_file_shm_hugepages(struct file *file)
548 {
549         return file->f_op == &shm_file_operations_huge;
550 }
551
552 static const struct vm_operations_struct shm_vm_ops = {
553         .open   = shm_open,     /* callback for a new vm-area open */
554         .close  = shm_close,    /* callback for when the vm-area is released */
555         .fault  = shm_fault,
556         .split  = shm_split,
557 #if defined(CONFIG_NUMA)
558         .set_policy = shm_set_policy,
559         .get_policy = shm_get_policy,
560 #endif
561 };
562
563 /**
564  * newseg - Create a new shared memory segment
565  * @ns: namespace
566  * @params: ptr to the structure that contains key, size and shmflg
567  *
568  * Called with shm_ids.rwsem held as a writer.
569  */
570 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
571 {
572         key_t key = params->key;
573         int shmflg = params->flg;
574         size_t size = params->u.size;
575         int error;
576         struct shmid_kernel *shp;
577         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
578         struct file *file;
579         char name[13];
580         vm_flags_t acctflag = 0;
581
582         if (size < SHMMIN || size > ns->shm_ctlmax)
583                 return -EINVAL;
584
585         if (numpages << PAGE_SHIFT < size)
586                 return -ENOSPC;
587
588         if (ns->shm_tot + numpages < ns->shm_tot ||
589                         ns->shm_tot + numpages > ns->shm_ctlall)
590                 return -ENOSPC;
591
592         shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
593         if (unlikely(!shp))
594                 return -ENOMEM;
595
596         shp->shm_perm.key = key;
597         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
598         shp->mlock_user = NULL;
599
600         shp->shm_perm.security = NULL;
601         error = security_shm_alloc(&shp->shm_perm);
602         if (error) {
603                 kvfree(shp);
604                 return error;
605         }
606
607         sprintf(name, "SYSV%08x", key);
608         if (shmflg & SHM_HUGETLB) {
609                 struct hstate *hs;
610                 size_t hugesize;
611
612                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
613                 if (!hs) {
614                         error = -EINVAL;
615                         goto no_file;
616                 }
617                 hugesize = ALIGN(size, huge_page_size(hs));
618
619                 /* hugetlb_file_setup applies strict accounting */
620                 if (shmflg & SHM_NORESERVE)
621                         acctflag = VM_NORESERVE;
622                 file = hugetlb_file_setup(name, hugesize, acctflag,
623                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
624                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
625         } else {
626                 /*
627                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
628                  * if it's asked for.
629                  */
630                 if  ((shmflg & SHM_NORESERVE) &&
631                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
632                         acctflag = VM_NORESERVE;
633                 file = shmem_kernel_file_setup(name, size, acctflag);
634         }
635         error = PTR_ERR(file);
636         if (IS_ERR(file))
637                 goto no_file;
638
639         shp->shm_cprid = get_pid(task_tgid(current));
640         shp->shm_lprid = NULL;
641         shp->shm_atim = shp->shm_dtim = 0;
642         shp->shm_ctim = ktime_get_real_seconds();
643         shp->shm_segsz = size;
644         shp->shm_nattch = 0;
645         shp->shm_file = file;
646         shp->shm_creator = current;
647
648         /* ipc_addid() locks shp upon success. */
649         error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
650         if (error < 0)
651                 goto no_id;
652
653         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
654
655         /*
656          * shmid gets reported as "inode#" in /proc/pid/maps.
657          * proc-ps tools use this. Changing this will break them.
658          */
659         file_inode(file)->i_ino = shp->shm_perm.id;
660
661         ns->shm_tot += numpages;
662         error = shp->shm_perm.id;
663
664         ipc_unlock_object(&shp->shm_perm);
665         rcu_read_unlock();
666         return error;
667
668 no_id:
669         ipc_update_pid(&shp->shm_cprid, NULL);
670         ipc_update_pid(&shp->shm_lprid, NULL);
671         if (is_file_hugepages(file) && shp->mlock_user)
672                 user_shm_unlock(size, shp->mlock_user);
673         fput(file);
674 no_file:
675         call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
676         return error;
677 }
678
679 /*
680  * Called with shm_ids.rwsem and ipcp locked.
681  */
682 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
683                                 struct ipc_params *params)
684 {
685         struct shmid_kernel *shp;
686
687         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
688         if (shp->shm_segsz < params->u.size)
689                 return -EINVAL;
690
691         return 0;
692 }
693
694 long ksys_shmget(key_t key, size_t size, int shmflg)
695 {
696         struct ipc_namespace *ns;
697         static const struct ipc_ops shm_ops = {
698                 .getnew = newseg,
699                 .associate = security_shm_associate,
700                 .more_checks = shm_more_checks,
701         };
702         struct ipc_params shm_params;
703
704         ns = current->nsproxy->ipc_ns;
705
706         shm_params.key = key;
707         shm_params.flg = shmflg;
708         shm_params.u.size = size;
709
710         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
711 }
712
713 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
714 {
715         return ksys_shmget(key, size, shmflg);
716 }
717
718 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
719 {
720         switch (version) {
721         case IPC_64:
722                 return copy_to_user(buf, in, sizeof(*in));
723         case IPC_OLD:
724             {
725                 struct shmid_ds out;
726
727                 memset(&out, 0, sizeof(out));
728                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
729                 out.shm_segsz   = in->shm_segsz;
730                 out.shm_atime   = in->shm_atime;
731                 out.shm_dtime   = in->shm_dtime;
732                 out.shm_ctime   = in->shm_ctime;
733                 out.shm_cpid    = in->shm_cpid;
734                 out.shm_lpid    = in->shm_lpid;
735                 out.shm_nattch  = in->shm_nattch;
736
737                 return copy_to_user(buf, &out, sizeof(out));
738             }
739         default:
740                 return -EINVAL;
741         }
742 }
743
744 static inline unsigned long
745 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
746 {
747         switch (version) {
748         case IPC_64:
749                 if (copy_from_user(out, buf, sizeof(*out)))
750                         return -EFAULT;
751                 return 0;
752         case IPC_OLD:
753             {
754                 struct shmid_ds tbuf_old;
755
756                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
757                         return -EFAULT;
758
759                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
760                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
761                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
762
763                 return 0;
764             }
765         default:
766                 return -EINVAL;
767         }
768 }
769
770 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
771 {
772         switch (version) {
773         case IPC_64:
774                 return copy_to_user(buf, in, sizeof(*in));
775         case IPC_OLD:
776             {
777                 struct shminfo out;
778
779                 if (in->shmmax > INT_MAX)
780                         out.shmmax = INT_MAX;
781                 else
782                         out.shmmax = (int)in->shmmax;
783
784                 out.shmmin      = in->shmmin;
785                 out.shmmni      = in->shmmni;
786                 out.shmseg      = in->shmseg;
787                 out.shmall      = in->shmall;
788
789                 return copy_to_user(buf, &out, sizeof(out));
790             }
791         default:
792                 return -EINVAL;
793         }
794 }
795
796 /*
797  * Calculate and add used RSS and swap pages of a shm.
798  * Called with shm_ids.rwsem held as a reader
799  */
800 static void shm_add_rss_swap(struct shmid_kernel *shp,
801         unsigned long *rss_add, unsigned long *swp_add)
802 {
803         struct inode *inode;
804
805         inode = file_inode(shp->shm_file);
806
807         if (is_file_hugepages(shp->shm_file)) {
808                 struct address_space *mapping = inode->i_mapping;
809                 struct hstate *h = hstate_file(shp->shm_file);
810                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
811         } else {
812 #ifdef CONFIG_SHMEM
813                 struct shmem_inode_info *info = SHMEM_I(inode);
814
815                 spin_lock_irq(&info->lock);
816                 *rss_add += inode->i_mapping->nrpages;
817                 *swp_add += info->swapped;
818                 spin_unlock_irq(&info->lock);
819 #else
820                 *rss_add += inode->i_mapping->nrpages;
821 #endif
822         }
823 }
824
825 /*
826  * Called with shm_ids.rwsem held as a reader
827  */
828 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
829                 unsigned long *swp)
830 {
831         int next_id;
832         int total, in_use;
833
834         *rss = 0;
835         *swp = 0;
836
837         in_use = shm_ids(ns).in_use;
838
839         for (total = 0, next_id = 0; total < in_use; next_id++) {
840                 struct kern_ipc_perm *ipc;
841                 struct shmid_kernel *shp;
842
843                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
844                 if (ipc == NULL)
845                         continue;
846                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
847
848                 shm_add_rss_swap(shp, rss, swp);
849
850                 total++;
851         }
852 }
853
854 /*
855  * This function handles some shmctl commands which require the rwsem
856  * to be held in write mode.
857  * NOTE: no locks must be held, the rwsem is taken inside this function.
858  */
859 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
860                        struct shmid64_ds *shmid64)
861 {
862         struct kern_ipc_perm *ipcp;
863         struct shmid_kernel *shp;
864         int err;
865
866         down_write(&shm_ids(ns).rwsem);
867         rcu_read_lock();
868
869         ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
870                                       &shmid64->shm_perm, 0);
871         if (IS_ERR(ipcp)) {
872                 err = PTR_ERR(ipcp);
873                 goto out_unlock1;
874         }
875
876         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
877
878         err = security_shm_shmctl(&shp->shm_perm, cmd);
879         if (err)
880                 goto out_unlock1;
881
882         switch (cmd) {
883         case IPC_RMID:
884                 ipc_lock_object(&shp->shm_perm);
885                 /* do_shm_rmid unlocks the ipc object and rcu */
886                 do_shm_rmid(ns, ipcp);
887                 goto out_up;
888         case IPC_SET:
889                 ipc_lock_object(&shp->shm_perm);
890                 err = ipc_update_perm(&shmid64->shm_perm, ipcp);
891                 if (err)
892                         goto out_unlock0;
893                 shp->shm_ctim = ktime_get_real_seconds();
894                 break;
895         default:
896                 err = -EINVAL;
897                 goto out_unlock1;
898         }
899
900 out_unlock0:
901         ipc_unlock_object(&shp->shm_perm);
902 out_unlock1:
903         rcu_read_unlock();
904 out_up:
905         up_write(&shm_ids(ns).rwsem);
906         return err;
907 }
908
909 static int shmctl_ipc_info(struct ipc_namespace *ns,
910                            struct shminfo64 *shminfo)
911 {
912         int err = security_shm_shmctl(NULL, IPC_INFO);
913         if (!err) {
914                 memset(shminfo, 0, sizeof(*shminfo));
915                 shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
916                 shminfo->shmmax = ns->shm_ctlmax;
917                 shminfo->shmall = ns->shm_ctlall;
918                 shminfo->shmmin = SHMMIN;
919                 down_read(&shm_ids(ns).rwsem);
920                 err = ipc_get_maxid(&shm_ids(ns));
921                 up_read(&shm_ids(ns).rwsem);
922                 if (err < 0)
923                         err = 0;
924         }
925         return err;
926 }
927
928 static int shmctl_shm_info(struct ipc_namespace *ns,
929                            struct shm_info *shm_info)
930 {
931         int err = security_shm_shmctl(NULL, SHM_INFO);
932         if (!err) {
933                 memset(shm_info, 0, sizeof(*shm_info));
934                 down_read(&shm_ids(ns).rwsem);
935                 shm_info->used_ids = shm_ids(ns).in_use;
936                 shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
937                 shm_info->shm_tot = ns->shm_tot;
938                 shm_info->swap_attempts = 0;
939                 shm_info->swap_successes = 0;
940                 err = ipc_get_maxid(&shm_ids(ns));
941                 up_read(&shm_ids(ns).rwsem);
942                 if (err < 0)
943                         err = 0;
944         }
945         return err;
946 }
947
948 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
949                         int cmd, struct shmid64_ds *tbuf)
950 {
951         struct shmid_kernel *shp;
952         int id = 0;
953         int err;
954
955         memset(tbuf, 0, sizeof(*tbuf));
956
957         rcu_read_lock();
958         if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
959                 shp = shm_obtain_object(ns, shmid);
960                 if (IS_ERR(shp)) {
961                         err = PTR_ERR(shp);
962                         goto out_unlock;
963                 }
964                 id = shp->shm_perm.id;
965         } else { /* IPC_STAT */
966                 shp = shm_obtain_object_check(ns, shmid);
967                 if (IS_ERR(shp)) {
968                         err = PTR_ERR(shp);
969                         goto out_unlock;
970                 }
971         }
972
973         /*
974          * Semantically SHM_STAT_ANY ought to be identical to
975          * that functionality provided by the /proc/sysvipc/
976          * interface. As such, only audit these calls and
977          * do not do traditional S_IRUGO permission checks on
978          * the ipc object.
979          */
980         if (cmd == SHM_STAT_ANY)
981                 audit_ipc_obj(&shp->shm_perm);
982         else {
983                 err = -EACCES;
984                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
985                         goto out_unlock;
986         }
987
988         err = security_shm_shmctl(&shp->shm_perm, cmd);
989         if (err)
990                 goto out_unlock;
991
992         ipc_lock_object(&shp->shm_perm);
993
994         if (!ipc_valid_object(&shp->shm_perm)) {
995                 ipc_unlock_object(&shp->shm_perm);
996                 err = -EIDRM;
997                 goto out_unlock;
998         }
999
1000         kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
1001         tbuf->shm_segsz = shp->shm_segsz;
1002         tbuf->shm_atime = shp->shm_atim;
1003         tbuf->shm_dtime = shp->shm_dtim;
1004         tbuf->shm_ctime = shp->shm_ctim;
1005         tbuf->shm_cpid  = pid_vnr(shp->shm_cprid);
1006         tbuf->shm_lpid  = pid_vnr(shp->shm_lprid);
1007         tbuf->shm_nattch = shp->shm_nattch;
1008
1009         ipc_unlock_object(&shp->shm_perm);
1010         rcu_read_unlock();
1011         return id;
1012
1013 out_unlock:
1014         rcu_read_unlock();
1015         return err;
1016 }
1017
1018 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
1019 {
1020         struct shmid_kernel *shp;
1021         struct file *shm_file;
1022         int err;
1023
1024         rcu_read_lock();
1025         shp = shm_obtain_object_check(ns, shmid);
1026         if (IS_ERR(shp)) {
1027                 err = PTR_ERR(shp);
1028                 goto out_unlock1;
1029         }
1030
1031         audit_ipc_obj(&(shp->shm_perm));
1032         err = security_shm_shmctl(&shp->shm_perm, cmd);
1033         if (err)
1034                 goto out_unlock1;
1035
1036         ipc_lock_object(&shp->shm_perm);
1037
1038         /* check if shm_destroy() is tearing down shp */
1039         if (!ipc_valid_object(&shp->shm_perm)) {
1040                 err = -EIDRM;
1041                 goto out_unlock0;
1042         }
1043
1044         if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1045                 kuid_t euid = current_euid();
1046
1047                 if (!uid_eq(euid, shp->shm_perm.uid) &&
1048                     !uid_eq(euid, shp->shm_perm.cuid)) {
1049                         err = -EPERM;
1050                         goto out_unlock0;
1051                 }
1052                 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1053                         err = -EPERM;
1054                         goto out_unlock0;
1055                 }
1056         }
1057
1058         shm_file = shp->shm_file;
1059         if (is_file_hugepages(shm_file))
1060                 goto out_unlock0;
1061
1062         if (cmd == SHM_LOCK) {
1063                 struct user_struct *user = current_user();
1064
1065                 err = shmem_lock(shm_file, 1, user);
1066                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1067                         shp->shm_perm.mode |= SHM_LOCKED;
1068                         shp->mlock_user = user;
1069                 }
1070                 goto out_unlock0;
1071         }
1072
1073         /* SHM_UNLOCK */
1074         if (!(shp->shm_perm.mode & SHM_LOCKED))
1075                 goto out_unlock0;
1076         shmem_lock(shm_file, 0, shp->mlock_user);
1077         shp->shm_perm.mode &= ~SHM_LOCKED;
1078         shp->mlock_user = NULL;
1079         get_file(shm_file);
1080         ipc_unlock_object(&shp->shm_perm);
1081         rcu_read_unlock();
1082         shmem_unlock_mapping(shm_file->f_mapping);
1083
1084         fput(shm_file);
1085         return err;
1086
1087 out_unlock0:
1088         ipc_unlock_object(&shp->shm_perm);
1089 out_unlock1:
1090         rcu_read_unlock();
1091         return err;
1092 }
1093
1094 long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1095 {
1096         int err, version;
1097         struct ipc_namespace *ns;
1098         struct shmid64_ds sem64;
1099
1100         if (cmd < 0 || shmid < 0)
1101                 return -EINVAL;
1102
1103         version = ipc_parse_version(&cmd);
1104         ns = current->nsproxy->ipc_ns;
1105
1106         switch (cmd) {
1107         case IPC_INFO: {
1108                 struct shminfo64 shminfo;
1109                 err = shmctl_ipc_info(ns, &shminfo);
1110                 if (err < 0)
1111                         return err;
1112                 if (copy_shminfo_to_user(buf, &shminfo, version))
1113                         err = -EFAULT;
1114                 return err;
1115         }
1116         case SHM_INFO: {
1117                 struct shm_info shm_info;
1118                 err = shmctl_shm_info(ns, &shm_info);
1119                 if (err < 0)
1120                         return err;
1121                 if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1122                         err = -EFAULT;
1123                 return err;
1124         }
1125         case SHM_STAT:
1126         case SHM_STAT_ANY:
1127         case IPC_STAT: {
1128                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1129                 if (err < 0)
1130                         return err;
1131                 if (copy_shmid_to_user(buf, &sem64, version))
1132                         err = -EFAULT;
1133                 return err;
1134         }
1135         case IPC_SET:
1136                 if (copy_shmid_from_user(&sem64, buf, version))
1137                         return -EFAULT;
1138                 /* fallthru */
1139         case IPC_RMID:
1140                 return shmctl_down(ns, shmid, cmd, &sem64);
1141         case SHM_LOCK:
1142         case SHM_UNLOCK:
1143                 return shmctl_do_lock(ns, shmid, cmd);
1144         default:
1145                 return -EINVAL;
1146         }
1147 }
1148
1149 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1150 {
1151         return ksys_shmctl(shmid, cmd, buf);
1152 }
1153
1154 #ifdef CONFIG_COMPAT
1155
1156 struct compat_shmid_ds {
1157         struct compat_ipc_perm shm_perm;
1158         int shm_segsz;
1159         compat_time_t shm_atime;
1160         compat_time_t shm_dtime;
1161         compat_time_t shm_ctime;
1162         compat_ipc_pid_t shm_cpid;
1163         compat_ipc_pid_t shm_lpid;
1164         unsigned short shm_nattch;
1165         unsigned short shm_unused;
1166         compat_uptr_t shm_unused2;
1167         compat_uptr_t shm_unused3;
1168 };
1169
1170 struct compat_shminfo64 {
1171         compat_ulong_t shmmax;
1172         compat_ulong_t shmmin;
1173         compat_ulong_t shmmni;
1174         compat_ulong_t shmseg;
1175         compat_ulong_t shmall;
1176         compat_ulong_t __unused1;
1177         compat_ulong_t __unused2;
1178         compat_ulong_t __unused3;
1179         compat_ulong_t __unused4;
1180 };
1181
1182 struct compat_shm_info {
1183         compat_int_t used_ids;
1184         compat_ulong_t shm_tot, shm_rss, shm_swp;
1185         compat_ulong_t swap_attempts, swap_successes;
1186 };
1187
1188 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1189                                         int version)
1190 {
1191         if (in->shmmax > INT_MAX)
1192                 in->shmmax = INT_MAX;
1193         if (version == IPC_64) {
1194                 struct compat_shminfo64 info;
1195                 memset(&info, 0, sizeof(info));
1196                 info.shmmax = in->shmmax;
1197                 info.shmmin = in->shmmin;
1198                 info.shmmni = in->shmmni;
1199                 info.shmseg = in->shmseg;
1200                 info.shmall = in->shmall;
1201                 return copy_to_user(buf, &info, sizeof(info));
1202         } else {
1203                 struct shminfo info;
1204                 memset(&info, 0, sizeof(info));
1205                 info.shmmax = in->shmmax;
1206                 info.shmmin = in->shmmin;
1207                 info.shmmni = in->shmmni;
1208                 info.shmseg = in->shmseg;
1209                 info.shmall = in->shmall;
1210                 return copy_to_user(buf, &info, sizeof(info));
1211         }
1212 }
1213
1214 static int put_compat_shm_info(struct shm_info *ip,
1215                                 struct compat_shm_info __user *uip)
1216 {
1217         struct compat_shm_info info;
1218
1219         memset(&info, 0, sizeof(info));
1220         info.used_ids = ip->used_ids;
1221         info.shm_tot = ip->shm_tot;
1222         info.shm_rss = ip->shm_rss;
1223         info.shm_swp = ip->shm_swp;
1224         info.swap_attempts = ip->swap_attempts;
1225         info.swap_successes = ip->swap_successes;
1226         return copy_to_user(uip, &info, sizeof(info));
1227 }
1228
1229 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1230                                         int version)
1231 {
1232         if (version == IPC_64) {
1233                 struct compat_shmid64_ds v;
1234                 memset(&v, 0, sizeof(v));
1235                 to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1236                 v.shm_atime = in->shm_atime;
1237                 v.shm_dtime = in->shm_dtime;
1238                 v.shm_ctime = in->shm_ctime;
1239                 v.shm_segsz = in->shm_segsz;
1240                 v.shm_nattch = in->shm_nattch;
1241                 v.shm_cpid = in->shm_cpid;
1242                 v.shm_lpid = in->shm_lpid;
1243                 return copy_to_user(buf, &v, sizeof(v));
1244         } else {
1245                 struct compat_shmid_ds v;
1246                 memset(&v, 0, sizeof(v));
1247                 to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1248                 v.shm_perm.key = in->shm_perm.key;
1249                 v.shm_atime = in->shm_atime;
1250                 v.shm_dtime = in->shm_dtime;
1251                 v.shm_ctime = in->shm_ctime;
1252                 v.shm_segsz = in->shm_segsz;
1253                 v.shm_nattch = in->shm_nattch;
1254                 v.shm_cpid = in->shm_cpid;
1255                 v.shm_lpid = in->shm_lpid;
1256                 return copy_to_user(buf, &v, sizeof(v));
1257         }
1258 }
1259
1260 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1261                                         int version)
1262 {
1263         memset(out, 0, sizeof(*out));
1264         if (version == IPC_64) {
1265                 struct compat_shmid64_ds __user *p = buf;
1266                 return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1267         } else {
1268                 struct compat_shmid_ds __user *p = buf;
1269                 return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1270         }
1271 }
1272
1273 long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr)
1274 {
1275         struct ipc_namespace *ns;
1276         struct shmid64_ds sem64;
1277         int version = compat_ipc_parse_version(&cmd);
1278         int err;
1279
1280         ns = current->nsproxy->ipc_ns;
1281
1282         if (cmd < 0 || shmid < 0)
1283                 return -EINVAL;
1284
1285         switch (cmd) {
1286         case IPC_INFO: {
1287                 struct shminfo64 shminfo;
1288                 err = shmctl_ipc_info(ns, &shminfo);
1289                 if (err < 0)
1290                         return err;
1291                 if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1292                         err = -EFAULT;
1293                 return err;
1294         }
1295         case SHM_INFO: {
1296                 struct shm_info shm_info;
1297                 err = shmctl_shm_info(ns, &shm_info);
1298                 if (err < 0)
1299                         return err;
1300                 if (put_compat_shm_info(&shm_info, uptr))
1301                         err = -EFAULT;
1302                 return err;
1303         }
1304         case IPC_STAT:
1305         case SHM_STAT_ANY:
1306         case SHM_STAT:
1307                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1308                 if (err < 0)
1309                         return err;
1310                 if (copy_compat_shmid_to_user(uptr, &sem64, version))
1311                         err = -EFAULT;
1312                 return err;
1313
1314         case IPC_SET:
1315                 if (copy_compat_shmid_from_user(&sem64, uptr, version))
1316                         return -EFAULT;
1317                 /* fallthru */
1318         case IPC_RMID:
1319                 return shmctl_down(ns, shmid, cmd, &sem64);
1320         case SHM_LOCK:
1321         case SHM_UNLOCK:
1322                 return shmctl_do_lock(ns, shmid, cmd);
1323                 break;
1324         default:
1325                 return -EINVAL;
1326         }
1327         return err;
1328 }
1329
1330 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1331 {
1332         return compat_ksys_shmctl(shmid, cmd, uptr);
1333 }
1334 #endif
1335
1336 /*
1337  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1338  *
1339  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1340  * "raddr" thing points to kernel space, and there has to be a wrapper around
1341  * this.
1342  */
1343 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1344               ulong *raddr, unsigned long shmlba)
1345 {
1346         struct shmid_kernel *shp;
1347         unsigned long addr = (unsigned long)shmaddr;
1348         unsigned long size;
1349         struct file *file;
1350         int    err;
1351         unsigned long flags = MAP_SHARED;
1352         unsigned long prot;
1353         int acc_mode;
1354         struct ipc_namespace *ns;
1355         struct shm_file_data *sfd;
1356         struct path path;
1357         fmode_t f_mode;
1358         unsigned long populate = 0;
1359
1360         err = -EINVAL;
1361         if (shmid < 0)
1362                 goto out;
1363
1364         if (addr) {
1365                 if (addr & (shmlba - 1)) {
1366                         if (shmflg & SHM_RND)
1367                                 addr &= ~(shmlba - 1);  /* round down */
1368                         else
1369 #ifndef __ARCH_FORCE_SHMLBA
1370                                 if (addr & ~PAGE_MASK)
1371 #endif
1372                                         goto out;
1373                 }
1374
1375                 flags |= MAP_FIXED;
1376         } else if ((shmflg & SHM_REMAP))
1377                 goto out;
1378
1379         if (shmflg & SHM_RDONLY) {
1380                 prot = PROT_READ;
1381                 acc_mode = S_IRUGO;
1382                 f_mode = FMODE_READ;
1383         } else {
1384                 prot = PROT_READ | PROT_WRITE;
1385                 acc_mode = S_IRUGO | S_IWUGO;
1386                 f_mode = FMODE_READ | FMODE_WRITE;
1387         }
1388         if (shmflg & SHM_EXEC) {
1389                 prot |= PROT_EXEC;
1390                 acc_mode |= S_IXUGO;
1391         }
1392
1393         /*
1394          * We cannot rely on the fs check since SYSV IPC does have an
1395          * additional creator id...
1396          */
1397         ns = current->nsproxy->ipc_ns;
1398         rcu_read_lock();
1399         shp = shm_obtain_object_check(ns, shmid);
1400         if (IS_ERR(shp)) {
1401                 err = PTR_ERR(shp);
1402                 goto out_unlock;
1403         }
1404
1405         err = -EACCES;
1406         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1407                 goto out_unlock;
1408
1409         err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
1410         if (err)
1411                 goto out_unlock;
1412
1413         ipc_lock_object(&shp->shm_perm);
1414
1415         /* check if shm_destroy() is tearing down shp */
1416         if (!ipc_valid_object(&shp->shm_perm)) {
1417                 ipc_unlock_object(&shp->shm_perm);
1418                 err = -EIDRM;
1419                 goto out_unlock;
1420         }
1421
1422         path = shp->shm_file->f_path;
1423         path_get(&path);
1424         shp->shm_nattch++;
1425         size = i_size_read(d_inode(path.dentry));
1426         ipc_unlock_object(&shp->shm_perm);
1427         rcu_read_unlock();
1428
1429         err = -ENOMEM;
1430         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1431         if (!sfd) {
1432                 path_put(&path);
1433                 goto out_nattch;
1434         }
1435
1436         file = alloc_file(&path, f_mode,
1437                           is_file_hugepages(shp->shm_file) ?
1438                                 &shm_file_operations_huge :
1439                                 &shm_file_operations);
1440         err = PTR_ERR(file);
1441         if (IS_ERR(file)) {
1442                 kfree(sfd);
1443                 path_put(&path);
1444                 goto out_nattch;
1445         }
1446
1447         file->private_data = sfd;
1448         file->f_mapping = shp->shm_file->f_mapping;
1449         sfd->id = shp->shm_perm.id;
1450         sfd->ns = get_ipc_ns(ns);
1451         /*
1452          * We need to take a reference to the real shm file to prevent the
1453          * pointer from becoming stale in cases where the lifetime of the outer
1454          * file extends beyond that of the shm segment.  It's not usually
1455          * possible, but it can happen during remap_file_pages() emulation as
1456          * that unmaps the memory, then does ->mmap() via file reference only.
1457          * We'll deny the ->mmap() if the shm segment was since removed, but to
1458          * detect shm ID reuse we need to compare the file pointers.
1459          */
1460         sfd->file = get_file(shp->shm_file);
1461         sfd->vm_ops = NULL;
1462
1463         err = security_mmap_file(file, prot, flags);
1464         if (err)
1465                 goto out_fput;
1466
1467         if (down_write_killable(&current->mm->mmap_sem)) {
1468                 err = -EINTR;
1469                 goto out_fput;
1470         }
1471
1472         if (addr && !(shmflg & SHM_REMAP)) {
1473                 err = -EINVAL;
1474                 if (addr + size < addr)
1475                         goto invalid;
1476
1477                 if (find_vma_intersection(current->mm, addr, addr + size))
1478                         goto invalid;
1479         }
1480
1481         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
1482         *raddr = addr;
1483         err = 0;
1484         if (IS_ERR_VALUE(addr))
1485                 err = (long)addr;
1486 invalid:
1487         up_write(&current->mm->mmap_sem);
1488         if (populate)
1489                 mm_populate(addr, populate);
1490
1491 out_fput:
1492         fput(file);
1493
1494 out_nattch:
1495         down_write(&shm_ids(ns).rwsem);
1496         shp = shm_lock(ns, shmid);
1497         shp->shm_nattch--;
1498         if (shm_may_destroy(ns, shp))
1499                 shm_destroy(ns, shp);
1500         else
1501                 shm_unlock(shp);
1502         up_write(&shm_ids(ns).rwsem);
1503         return err;
1504
1505 out_unlock:
1506         rcu_read_unlock();
1507 out:
1508         return err;
1509 }
1510
1511 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1512 {
1513         unsigned long ret;
1514         long err;
1515
1516         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1517         if (err)
1518                 return err;
1519         force_successful_syscall_return();
1520         return (long)ret;
1521 }
1522
1523 #ifdef CONFIG_COMPAT
1524
1525 #ifndef COMPAT_SHMLBA
1526 #define COMPAT_SHMLBA   SHMLBA
1527 #endif
1528
1529 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1530 {
1531         unsigned long ret;
1532         long err;
1533
1534         err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1535         if (err)
1536                 return err;
1537         force_successful_syscall_return();
1538         return (long)ret;
1539 }
1540 #endif
1541
1542 /*
1543  * detach and kill segment if marked destroyed.
1544  * The work is done in shm_close.
1545  */
1546 long ksys_shmdt(char __user *shmaddr)
1547 {
1548         struct mm_struct *mm = current->mm;
1549         struct vm_area_struct *vma;
1550         unsigned long addr = (unsigned long)shmaddr;
1551         int retval = -EINVAL;
1552 #ifdef CONFIG_MMU
1553         loff_t size = 0;
1554         struct file *file;
1555         struct vm_area_struct *next;
1556 #endif
1557
1558         if (addr & ~PAGE_MASK)
1559                 return retval;
1560
1561         if (down_write_killable(&mm->mmap_sem))
1562                 return -EINTR;
1563
1564         /*
1565          * This function tries to be smart and unmap shm segments that
1566          * were modified by partial mlock or munmap calls:
1567          * - It first determines the size of the shm segment that should be
1568          *   unmapped: It searches for a vma that is backed by shm and that
1569          *   started at address shmaddr. It records it's size and then unmaps
1570          *   it.
1571          * - Then it unmaps all shm vmas that started at shmaddr and that
1572          *   are within the initially determined size and that are from the
1573          *   same shm segment from which we determined the size.
1574          * Errors from do_munmap are ignored: the function only fails if
1575          * it's called with invalid parameters or if it's called to unmap
1576          * a part of a vma. Both calls in this function are for full vmas,
1577          * the parameters are directly copied from the vma itself and always
1578          * valid - therefore do_munmap cannot fail. (famous last words?)
1579          */
1580         /*
1581          * If it had been mremap()'d, the starting address would not
1582          * match the usual checks anyway. So assume all vma's are
1583          * above the starting address given.
1584          */
1585         vma = find_vma(mm, addr);
1586
1587 #ifdef CONFIG_MMU
1588         while (vma) {
1589                 next = vma->vm_next;
1590
1591                 /*
1592                  * Check if the starting address would match, i.e. it's
1593                  * a fragment created by mprotect() and/or munmap(), or it
1594                  * otherwise it starts at this address with no hassles.
1595                  */
1596                 if ((vma->vm_ops == &shm_vm_ops) &&
1597                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1598
1599                         /*
1600                          * Record the file of the shm segment being
1601                          * unmapped.  With mremap(), someone could place
1602                          * page from another segment but with equal offsets
1603                          * in the range we are unmapping.
1604                          */
1605                         file = vma->vm_file;
1606                         size = i_size_read(file_inode(vma->vm_file));
1607                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1608                         /*
1609                          * We discovered the size of the shm segment, so
1610                          * break out of here and fall through to the next
1611                          * loop that uses the size information to stop
1612                          * searching for matching vma's.
1613                          */
1614                         retval = 0;
1615                         vma = next;
1616                         break;
1617                 }
1618                 vma = next;
1619         }
1620
1621         /*
1622          * We need look no further than the maximum address a fragment
1623          * could possibly have landed at. Also cast things to loff_t to
1624          * prevent overflows and make comparisons vs. equal-width types.
1625          */
1626         size = PAGE_ALIGN(size);
1627         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1628                 next = vma->vm_next;
1629
1630                 /* finding a matching vma now does not alter retval */
1631                 if ((vma->vm_ops == &shm_vm_ops) &&
1632                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1633                     (vma->vm_file == file))
1634                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1635                 vma = next;
1636         }
1637
1638 #else   /* CONFIG_MMU */
1639         /* under NOMMU conditions, the exact address to be destroyed must be
1640          * given
1641          */
1642         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1643                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1644                 retval = 0;
1645         }
1646
1647 #endif
1648
1649         up_write(&mm->mmap_sem);
1650         return retval;
1651 }
1652
1653 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1654 {
1655         return ksys_shmdt(shmaddr);
1656 }
1657
1658 #ifdef CONFIG_PROC_FS
1659 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1660 {
1661         struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1662         struct user_namespace *user_ns = seq_user_ns(s);
1663         struct kern_ipc_perm *ipcp = it;
1664         struct shmid_kernel *shp;
1665         unsigned long rss = 0, swp = 0;
1666
1667         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1668         shm_add_rss_swap(shp, &rss, &swp);
1669
1670 #if BITS_PER_LONG <= 32
1671 #define SIZE_SPEC "%10lu"
1672 #else
1673 #define SIZE_SPEC "%21lu"
1674 #endif
1675
1676         seq_printf(s,
1677                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1678                    "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1679                    SIZE_SPEC " " SIZE_SPEC "\n",
1680                    shp->shm_perm.key,
1681                    shp->shm_perm.id,
1682                    shp->shm_perm.mode,
1683                    shp->shm_segsz,
1684                    pid_nr_ns(shp->shm_cprid, pid_ns),
1685                    pid_nr_ns(shp->shm_lprid, pid_ns),
1686                    shp->shm_nattch,
1687                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1688                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1689                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1690                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1691                    shp->shm_atim,
1692                    shp->shm_dtim,
1693                    shp->shm_ctim,
1694                    rss * PAGE_SIZE,
1695                    swp * PAGE_SIZE);
1696
1697         return 0;
1698 }
1699 #endif